Process of bleaching animal fibers



e-iii sa. 56MB UNITED STATES PATENT OFFICE PROCESS OF BLEACHING ANIMAL FIBERS Constantine F. Fabian, Brookfield, Conn., and

Alexander N. Sachanen, Luxembourg, Luxembourg, assignors, by mesne assignments, to The Non-Mercuric Carrot Company, Danbury, Conn., a corporation of Connecticut No Drawing. Application March 12, 1935, Serial No. 10.674

3 Claims. (Cl. 8--2) This invention relates to the bleaching of animal fibers and more particularly to the bleaching of fur, such as cut fur, boiled fur, fur in felt forme -etc, the invention further reapt to be very high, increasing the wastage and expense. This high consumption of hydrogen peroxide in bleaching through alkaline solutions arises from the fact that hydrogen peroxide is composes with the formation of free oxygen, which does not produce any sensible bleaching effect upon the animal fibers.

Acid bleaching compositions do not act so The required duration of the treatment will depend on the freedom of circulation permitted by the vat and by the amount of fur in relation to the amount of solution as well as on the temperlating to compositions of matter adapted to be detrimentally upon the animal fibers, but their 5 employed in such bleaching treatment. bleaching action is too inadequate to be availed One object of this invention is to provide a of since they do not act with sufficient efiect bleaching composition and treatment with a to remove the films or coatings of foreign matter satisfactory bleaching effect but without any encasing the fibers.

10 substantial detrimental action upon the treated We have found that the detrimental action 10 animal fibers. of the alkaline reagents upon animal fibers may It is well known that alkaline bleaching solube materially reduced, if not substantially tions, particularly when employed with hydroavoided, by dividing the bleaching process into gen peroxide, have in general a strong bleaching two consecutive steps or operations, in the first action. But alkaline bleaching solutions adeof which treatment with an alkaline bath is 15 quate togive a satisfactory bleaching effect also employed for the preparation of the material to tend detrimentally to affect the properties of be bleached, and in the second of which the the treated animal fibers, with deterioration in bl aching is acc mpli by atm nt in a their strength and the production of a harshslightly acid bleaching solution prepared as ness under feel or touch. As a matter of fact, hereinafter described. I 20 all alkaline solutions tend to dissolve and de- In the first or preliminary treatment, which compose animal fibers into products of decommay be of r la iv ly h r d r i n as mp position which are soluble in water. to the succeeding treatment, the animal fibers Generally speaking, the action of an alkaline e Subjected iq. q lll iliiyely weak alkaline solusolution is beneficial to the extent that it acts o o mf' fi e aS 8 1 bic b 25 to remove from the surface of the fibers the bisodium pho p greasy or waxy film-like covering which encases e'fi e alkaline Salt of a 10W D Value and interferes with the bleaching of the fib r is recommended since the solution then provides by preventing the bleaching agent from acting a relatively mild action on the fur which is cfby oxidation on the pigment contained within f iv f r h in n p rp se but can be 30 the fibers. Such action, however, is injurious if easily Co olled and terminated at the most prolonged beyond that stage and if continued, favorable time without detrimental efiect on as in the case of the alkaline bleaching soluthe u tions referred to, during the time that the This P a y t at t ay be Ca ied out v bleaching agent is acting to bleach the fiberth ough the use O the a a e bath a o e, but 35 contained pigment, for during such time the in the practical application of the process to the alkaline solution is still active in attacking and t a m nt of u i large a u ts n a sin le destroying the substance of the fiber itself, bath where a free penetration of the solution to Any particular fur which is designed for feltall parts of the fur may be more or less haming purposes, as, for example, in the manufacpered, as w as for t pu p s f sh t n 4o ture of hats, when bleached with alkaline soluthe time required for the treatment, the latter tions tends to lose its felting capacity as well is pr f rab y a i d out in the presence of s m as its afiinity to dye stuffs. Consequently fur penetrating or accelerating agent designed to bleached with alkaline solutions should not be facilitate the penetration of the water and the used even as a filler in mixture with carroted reagents into the fibers. sul phoi atsedpa lyniine fur in making felt hats, since it is apt to prol h ls aild slllpllggatepetrlqlellm duce undyed or yellow tinged spots after the ,F L L 91mins;.such penetration. dyeing operation. In subjecting cut or boiled fur to thisprelim- Furthermore the consumption of hydrogen inary treatment, the fur is placed in a vat or like peroxide in bleaching by alkaline solutions is receptacle and there immersed in the solution. 50

very unstable in such solutions and partly deature of the solution. With reasonably free circulation of the solution through the fur and with the bath maintained at a temperature of from 80 to 90 F., this preliminary treatment ordinarily requires from one to two hours, the most suitable time being more exactly ascertainable by the results of one or more initial tests.

In the case of bleaching uncut fur on the skins the solution may be sprayed or brushed on the fur to thoroughly wet the same, after which the skins are allowed to stand for about one hour before cleansing them.

Following the the treatment'with the alkaline bath, the remnants of the alkaline solution are removed from the treated fibers in any suitable manner.

The removal of the alkaline solution is conveniently accomplished by placing the treated fur immediately on removal from the bath in a centrifugal dryer, removing the majorpart of the alkaline solution by operating the dryer, and then, while continuing the operation of the dryer, spraying water on the fur until all alkaline traces are removed, after which the operation of the dryer is continued long enough to remove surplus water from the fur.

In the second operation, the animal fibers, cleansed from the alkaline solution, are subsequently treated with a slightly acid and preferably almost neutral bleaching solution.

For this bleaching solution, we may, for example, employ a solution of hydrogen peroxide and a persulphate of an alkali metal including ammonium in the presence of calcium chloride or a similar salt of an alkali earth metal, persulphate being added as a bleaching agent of an acid character to build a slightly acid bath. Calcium chloride or similar salt of an alkali earth metal soluble in water is added to produce a retarding action on the bleaching process. When employed, and particularly when used after the preparatory treatment with the weak alkaline bath, it provides an even and uniform bleaching of the animal fibers not previously obtainable and also results in greater economy'in the consumption of hydrogen peroxide. Thus the solution of hydrogen peroxide and persulphate of an alkali metal or ammonium provides the desired weak acid reaction.

Either sodium persulphate, potassium persulphate or ammonium persulphate may be used as the alkali metal persulphate to provide the acidulating action for the bleaching bath. To provide the retarding action various salts.- of alkali metals may be employed, such as magnesium, barium and strontium chlorides, magnesium sulphate and magnesium, calcium, barium and strontium nitrates.

In some cases it may be advisable to neutralize a surplus of acidity in this solution in order to keep a certain pI-I. For this purpose we may use a weak alkaline solution of such salts as borax, bisodium phosphate, etc. For example, in the instance given we may add to the bleaching solution a solution of borax until the initial precipitation of calcium borate begins. Care should be taken, however, that this is not carried to the point where the bleaching solution forms any appreciable quantity of the precipitate. This provides a simple and certain method of getting a bleaching solution which is only slightly acid, by first making it more acid than desired and then by neutralization reducing its acidity to the stage required. The addition of the borax acts to check the surplus of acidity in the solution and yield a solution having a slightly acid reaction, giving a satisfactory bleaching effect.

Treatment of the animal fibers in the second step or operation with the slightly acid bleaching solution is continued for a relatively longer time than treatment in the first preparative step or operation. Thus the animal fibers are not bleached in the alkaline solution but are there preliminarily treated and prepared for the following bleaching operation which takes place in a slightly acid or almost neutral bath. In this manner we avoid the strong hydrolyzing and decomposing eifects of the alkaline solutions during oxidization by hydrogen peroxide. At the same time the amount of bleaching reagents consumed by our process is very materially reduced.

The following examples illustrate our invention.

For'cut fur or boiled rabbit fur (fur from the legs, tails and ends of rabbit skins which have been boiled in sulphuric acid), the fur is placed into a 1-2% aqueous solution of borax to which is added about of a sulphonated alcohol, such, for example, as that known as gardinol, to act as penetrator. The fur remains in this bath about 1-2 hours, at the temperature of about 35 C. After this first preliminary operation, the treated fur is placed in a centrifugal dryer and dried and washed, and then placed in a bleaching bath. The bleaching bath is an aqueous solution of about /g1% of hydrogen peroxide, about 1-2% of sodium persulphate, and about 1% of calcium chloride. This weak acid solution is partly neutralized by addition of the aqueous solution of bisodium phosphate, which addition is terminated when the initial precipitation of calcium phosphate begins, leaving the final solution with a very weak acid reaction. The fur to be bleached remains in the bleaching bath about -8 hours at the temperature of about 35 C. The centrifugal drying and washing operations follow after the bleaching.

After the described bleaching process the fur turns white without any damaging effect on its quality.

The amount of borax used in the weak alkaline solution for the preparatory treatment may vary approximately from to 3% but it is preferably kept within from 1 to 2%. Sodium bicarbonate and bisodium phosphate, if employed, are used in the same proportions. In the bleaching solution hydrogen peroxide may vary approximately from to 3 /z% and the amount of sodium persulphate approximately from 1 to 5% with preference for the proportions stated in the example. Persulphates other than sodium persulphate are used in the same proportions, and salts of alkaline earths other than calcium chloride when used are preferably employed in proportions varying but little from that stated (1%) in the example.

Gray hat bodies before sizing may be bleached by a similar process-first through a preparatory treatment with a similar weak alkaline bath, and then through a bleaching treatment with a weak acid bath. In the case of gray hat bodies, however, the bleaching solution should be more concentrated, the degree of concentration depending on the shade or color of the hat bodies to be bleached. With light shades no substantial difierence may be necessary in the proportions of the ingredients given in the above example for the bleaching bath. With darker shades the proportions of 8. ELEACHENG 6r DYEING; FLUID iiiE/HMENT (it CHEIVHCAL MOBEFL "ATEON F TEXTILES (it FIBERS,

those ingredients should be increased, and with very dark shades may have to be doubled. After being subjected to these two operations, the gray hat bodies are much lighter in color, without any resulting damage to their-iquality. It should be observed, however, that-the bleaching efiect for boiled orout fur is much more pronounced than for gray hat bodies.

In treating uncut fur on the skins by brushing or spraying both the alkaline and the bleaching solutions should be used in greater concentrations than are given, in the above example. For greater concentrations of the bleaching solution the. proportions of hydrogen peroxide and persulphate' maybe increased in equal ratio but no particular increase in the proportions of calcium chloride will ordinarily be required.

We have found that for bleaching cut fur, and especially in bleaching gray hat bodies, enforced circulation of the bleaching solution, which is impracticable in the case of unstable alkaline-hydrogen peroxide bleaching solutions due to the resulting decomposition of hydrogen peroxide, not only shortens the time required for bleaching but promotes and improves the bleaching itself. Such enforced circulation may be readily had by continuously pumping the bleaching solution into, through and out of the vat or tank containing the fur or the gray hat bodies, and. then causing its recirculation therethrough.

Various changes and departures from the proportions and from the specific ingredients of Search H00:

our bleaching composition herein described. may be :made andalso fromthe exact steps herein set forth, all within the scope and principles of our generic invention, it being understood that the matter hereinbeiore setuforth is submitted as illustrative and not in a limiting sense.

We claim:

1. The process of bleaching animal ,tlbers, which consists in treating the fibers with a weak non-oxidizing alkaline solution, thoroughly washing the fibers to remove traces of .alkali, and subsequently treating them with a slightly acid bleaching solution containing hydrogen peroxide, an alkali metal persulphate and a salt of an alkaline earth.

2. The process of bleaching animal fibers, which consists in treating the fibers with a weak non-oxidizing alkaline solution, thoroughly washing the fibers to remove traces of alkali, and subsequently treating them with a slightly acid bleaching solution containing hydrogen peroxide, sodium persulphate and calcium chloride.

3. The process of bleaching vanimal fibers, which consists in treating the fibers with a weak non-oxidizing alkaline solution, thoroughly washing theufibers, and subsequently treating them with a-islightly acid bleaching solution containing from to 3 /2% of hydrogen peroxide, from 1 to 5% of a persulphate, and approximately 1% of the salt of an alkaline earth.

CONSTAN'I'INE F. FABIAN. ALEXANDER N. SACHANEN. 

